Sea Claims 10cm of Canarian Coast in Three Decades
The sea has gained ten centimetres of ground on the Canary Islands’ coasts over the last 30 years. The progressive increase in global temperatures has caused the ocean to conquer territory that, at the end of the 20th century, belonged to the land. This is a trend that, far from slowing down, is accelerating. It is expected that in just 25 years, the Canaries could lose 40 centimetres of land to the sea. This will cause maritime storms, like the one affecting the Islands today, to occur more frequently and with greater intensity.
Scientific Study Reveals Accelerating Trend
This is the conclusion of a recent scientific study conducted by two researchers from the University of Las Palmas de Gran Canaria (ULPGC), Mikel Ibeas and Antonio Martínez-Marrero, published in the Journal of Marine Science and Engineering. After reviewing data collected by tide gauges and satellites between January 1993 and December 2022 at two points in the archipelago (the port of Santa Cruz de Tenerife and the port of Las Palmas de Gran Canaria) – the longest and most robust data series available for the area – the researchers confirmed the upward trend in sea level, which is rising at a rate of 3.5 millimetres per year.
This trend is slightly higher than that confirmed in studies from just two years ago. In fact, a 2023 study by the Spanish Institute of Oceanography (IEO), published in the journal Geosciences with data up to 2019, showed the sea level had risen by a maximum of three millimetres per year. That study, which analysed data from 1948, demonstrated that the rate had doubled since the 1990s.
A Non-Linear Rise Influenced by Ocean Currents
“By taking data from dates later than those in already published studies, we have been able to confirm that the rate of increase is growing,” explains Martínez-Marrero. This study goes a step further, describing a 21st-century sea-level rise that is not linear. Specifically, it establishes that the rate of sea-level rise slowed between 2000 and 2015, but then accelerated again between 2015 and 2022.
Furthermore, despite the detected trend, the researchers have confirmed that the rise has not been uniform across the region. According to them, these differences are due to the influence of oceanic eddies, which are the marine equivalents of atmospheric storms and anticyclones, capable of modifying the general ocean circulation in the area where they occur.
Consequently, where cyclonic eddies predominate, the increase has been smaller as they cause a depression of the sea surface, while in areas with a greater presence of anticyclonic eddies, the increase has been larger. The study also confirms that the land in the two archipelago capitals is undergoing slight subsidence, meaning the ground is sinking. This causes the relative sea level to rise by an additional 0.5 to 0.7 millimetres per year.
“This area has always had this subsidence, and although it is very small, it causes slight variations in the sea-level rise, which can reach 4 millimetres per year here,” indicates Martínez-Marrero.
Link to Atlantic Weather Patterns and Future Projections
The researchers also found a direct link between rising sea levels and variations in the North Atlantic Oscillation (NAO), which occur due to fluctuations in the atmospheric pressure difference between the Icelandic Low and the Azores High. “The mean annual increase fluctuates and goes up or down depending on the interannual changes of the NAO,” explains the researcher. The modifications the NAO causes in atmospheric and marine meteorology are similar to those produced in the Pacific Ocean with the El Niño and La Niña phenomena. Previous studies have also seen a “small relationship” between both currents.
As part of this work, an estimate of the mean sea-level rise in the Canaries by 2050 has been made, based on the three scenarios proposed by the United Nations Intergovernmental Panel on Climate Change. In the most pessimistic scenario, by the mid-21st century, the sea level could have risen by approximately 40 centimetres in Santa Cruz de Tenerife and 36 centimetres in Las Palmas de Gran Canaria compared to the mean level recorded in 2005.
Urgent Need for Adaptation Measures
Understanding how climate change is affecting sea levels in the Canaries is fundamental for adopting the necessary palliative and preventive measures to avoid the profound environmental damage this rise is causing and could cause in the future. This includes threats from flooding and coastal erosion to saltwater intrusion into underground aquifers, the loss of ecosystem diversity, and risks to infrastructure and services.
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